Eighty-five strains of marine bacteria were isolated from the Muroto deep seawater at a depth of 320m off the coast of Cape Muroto, Kochi Prefecture, Japan. The bacteria were analyzed based on the sequences of the 16S rRNA gene. Seventy-five strains were identified as 12 genera; 29 strains to the genus of Vibrio, 16 to Pseudoalteromonas, 9 to Shewanella, 6 to Alteromonas, 4 to Marinobacter, 3 to Erythrobacter, 2 to Tenacibaculum, 2 to Dietzia and 1 strain each to the genera of Bacillus, Halomonas, Idiomarina and Photobacterium. Some of these strains were closely related to known bacteria including psychrotrophs, barophilic bacteria and bacteria which decompose hydrocarbons. Some other strains produced pigments reported to have physiological activities. On the other hand, the remaining 10 unidentified strains contained novel bacteria whose DNA sequences showed low homology with those of the already identified bacteria. Thus, the Muroto deep seawater has been demonstrated to be an important source for investigations of unknown, yet potentially useful, bacteria.

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Republic of Fiji and many other countries in the tropical and subtropical areas desire both electric power by the ocean thermal energy conversion (OTEC) and drinking water from desalinated seawater. Then, a hybrid OTEC system combined with a desalination plant by use of deep ocean water is under consideration. For actual construction of the OTEC system, the choice of location is essentially important. In this paper, oceanographic data of seawater temperature, salinity and dissolved oxygen obtained off the coast of Suva of the Viti Levu Island of the Fiji islands in the Pacific Ocean at the beginning of December 1996, 1997, 1998 and 1999 are reported as well as bottom topography. The renewable energy available from the exclusive economic zone in the Fiji islands is estimated based on the oceanographic data obtained. Estimates of renewable energy by the two methods give about 120 and 1959 times as much as the current electric power in the Republic of Fiji, respectively.

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Concentrations of nitrate in deep seawater pumped up from 321 m in Toyama Bay were determined at an hour interval between September 2001 and March 2003 with a newly designed continuous fully-automated ion chromatography. Nitrate concentrations were usually around 24μM, but sometimes suddenly changed to 10.1 to 24.8μM for periods of several hours to several days. The decrease of nitrate concentration was found to be closely associated with temperature rise. It was thought that seawater masses having low nitrate concentration and high temperature might occasionally reach the inlet of the deep seawater intake pipe due to possible vertical and horizontal movements of seawater masses. Stormy weather in winter and typhoon in summer could be responsible for such seawater mass movements.

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Food production in the world is likely to become an urgent subject needing to be solved in the near future due to the steady increase of the world human population and the deterioration of farm lands for agriculture in the most productive areas. A large stock of nutrients in deep ocean water (DOW), below the euphotic zone of the world ocean, has great potential for enhancing existing marine production which could subsidize the production of animal protein on land. Three trials of ocean fertilization currently being carried out in Japan to increase fish and other marine products are summarized as follows: mixing more nutrientrich bottom water with nutrient-poor shallow water by means of an artificial seamount and prevailing current actions on the continental shelf; adding more nutrient-rich deep ocean water (DOW) to nutrient-poor surface water after it has been heated from passing it through electric power plants as a coolant; and directly discharging more nutrient-rich DOW to nutrient- poor shallow euphotic water as density current after mixing it with warm surface water.

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